I can't say enough good things about this water filter. Of all of Sawyer's portable water filters (all pointone family), this one is by far the most useful and the most used.
It comes with the reverse "syringe" to back wash the filter, a small aluminum dirty water back and a rubber hose/straw.
This thing is so unbelievably light, it's hard to believe it is a 0.1 micro filter. and it works fast. It may not be as hands free as a gravity filter, but it's way less work than a water pump. And water pumps have far great mechanical failure chances than this little guy. heck, I could carry two sets of these and still be lighter than just about every portable water filter I've seen (and those other ones are .2 microns).
It fits on most cheap water bottles with the smaller bottle cap. so you can re-cycle soda bottles or water bottles. the aluminum bag is best though, and Sawyer sells a larger 2 liter version that is super light, and rolls up to be compact. I bring two of the larger bags and one of the smaller bags. The smaller bag I use during hiking. the two larger ones I fill and cap at the camp site. It's dirty water, of course, so I just screw on the water filter when I want clean water and pour into a pot and boil.
0.1 microns is good for most things. and certainly better than 0.2 micron filters.
But, it's important to note that this is NOT a water purifier. if there are toxic chemicals in the "dirty" water, this will not filter them out. It will filter out bacteria, viruses, etc. So you should be able to just drink water collected from a stream or lake in the mountains. Just don't collect water from likely toxic areas like a large lake that has buildings and such. Generally, I hike in the emigrant wilderness, where there are no buildings by the lakes at 7500 feet and about. In fact, there's no one up there apart from park rangers and other backpackers, so this type of filter is more than adequate up there.
If you backpack in the wilderness...I would recommend this over a pump without a doubt. And frankly, I think it's better than a fravity filter because....again...fewer points of failure, and less weight to carry.